1. Field of the Invention
This invention relates to amorphous metal alloys and, more particularly, to cobalt rich amorphous metal alloys that include certain transition metal and metalloid elements.
2. Description of the Prior Art
There are three physical parameters which can inhibit the easy magnetization and demagnetization of magnetic materials: strong anisotropy, non-zero magnetostriction and, at high frequencies, low resistivity. Metallic glasses generally show resistivities greater than 100 micro ohm cm, whereas crystalline and polycrystalline magnetic metals generally show resistivities below 50 micro ohm cm. Also, because of their randomly disordered structures, metallic glasses are typically isotropic in their physical properties, including their magnetization. Because of these two characteristics, metallic glasses have an initial advantage over conventional magnetic metals. However, metallic glasses do not generally show zero magnetostriction. When zero magnetostriction glasses can be found they are generally good soft magnetic metals (R. C. O'Handley, B. A. Nesbitt, and L. I. Mendelsohn, IEEE Trans Mag-12, p. 942, 1976, U.S. Pat. Nos. 4,038,073 and 4,150,981), because they satisfy the three approved criteria. For this reason, interest in zero magnetostriction glasses has been intense as indicated by the many publications on low magnetostriction metallic glasses (A. W. Simpson and W. G. Clements, IEEE Trans Mag-11, p. 1338, 1975; N. Tsuya, K. I. Arai, Y. Shiraga and T. Masumoto, Phys. Lett. A51, p. 121, 1975; H. A. Brooks, Jour. Appl. Phys. 47, p. 334, 1975; T. Egami, P. J. Flanders and C. D. Graham, Jr., Appl. Phys. Lett. 26, p. 128, 1975 and AIP Conf. Proc. No. 24, p. 697, 1975; R. C. Sherwood, E. M. Gyorgy, H. S. Chen, S. D. Ferris, G. Norman and H. J. Leamy, AIP Conf. Proc. No. 24, p. 745, 1975; H. Fujimori, K. I. Arai, H. Shiraga, M. Yamada, T. Masumoto and N. Tsuya, Japan, Jour. Appl. Phys. 15, p. 705, 1976; L. Kraus and J. Schneider, phys. stat. sol. a39, p. K161, 1977; R. C. O'Handley in Amorphous Magnetism, edited by R. Levy and R. Hasegawa (Plenum Press, New York 1977), p. 379; R. C. O'Handley, Solid State Communications 21, p. 1119, 1977; R. C. O'Handley, Solid State Communications 22, p. 458, 1977; R. C. O'Handley, Phys. Rev. 18, p. 930, 1978; H. S. Chen, E. M. Gyorgy, H. J. Leamy and R. C. Sherwood, U.S. Pat. No. 4,056,411, Nov. 1, 1977).
The existence of a zero in the magnetostriction of Co-Mn-B glasses has been observed by H. Hiltzinger of Vacuumschmeltze A. G., Hanau, Germany.
Reference to Co-rich glasses containing 6 atom percent of Cr is made by N. Heiman, R. D. Hempstead and N. Kazama in Journal of Applied Physics, Vol. 49, p. 5663, 1978. Their interest was in improving the corrosion resistance of Co-B thin films. No reference to magnetostriction is made in that article.
Saturation moments and Curie temperatures of Co.sub.80-x T.sub.x P.sub.10 B.sub.10 glasses (T=Mn, Cr, or V) were recently reported by T. Mizoguchi in the Supplement to the Scientific Reports of RITU (Research Institutes of Tonoku University), A June 1978, p. 117. No reference to their magnetostrictive properties was reported.
In Journal of Applied Physics, Vol. 50, p. 7597, 1979, S. Ohnuma and T. Masumoto outline their studies of magnetization and magnetostriction in Co-Fe-B-Si glasses with light transition metal (Mn, Cr, V, W, Ta, Mo and Nb) substitutions. They show that the coercivity decreases and the effective permeability increases in the composition range near zero magnetostriction.
New applications requiring improved soft zero-magnetic materials that are easily fabricated and have excellent stability have necessitated efforts to develop further specific compositions.